The present invention relates in general to centrifuges and more particularly to an arrangement designed to prevent an ultracentrifuge rotor from exceeding a rotative speed which could result in a hazardous condition in the form of an uncontained explosion of the rotor.
Ultracentrifuges are generally intended for laboratory use and a rotor drive is arranged to make available any one of many possible speeds of rotation. Several sizes and types of rotors are generally supplied to accommodate for various types of work and different rotational speeds. Thus, one rotor may be adapted for one type of separating work and designed for speeds ranging up to 20,000 R.P.M., and another designed for higher speeds which may, for example, range up to 40,000 R.P.M. and another up to 50,000 R.P.M. There is always the possibility that an attendant may select the wrong rotor for the speed of the operation selected with the result that the safe speed of operation for a particular rotor is exceeded.
Because of the high rotative speeds employed in ultracentrifuge equipment, it is not possible to design all of the rotors employed with the centrifuge with a safety factor as high as might normally be considered good engineering practice, and therefore it is necessary to guard against excessive rotative speeds. Excessive speed may cause a rotor to burst or "explode" into a multitude of fragments and in the event of extremely high rotative energy forces, it is possible that some of these fragments may not be contained within the centrifuge housing and could likely injure an attendant or do great damage to the surrounding laboratory. It is desirable, therefore, to prevent the rotor from attaining a rotative speed at which such high energy is created.
In most instances, an electrical or mechanical speed control means is included as a part of the centrifuge or rotor and this will prevent a particular rotor from exceeding its designed speed. Examples of such safety devices are disclosed in U.S. Pat. Nos. 2,666,572 and 3,101,322, both of which are assigned to Beckman Instruments, Inc., the assignee of the present invention. There is, however, always the possibility that the electrical or mechanical speed control may fail to function properly and thereby permit the rotor to be driven at an excessive speed. The present invention is intended to provide a further or redundant measure of safety control over and above the normal type of speed control apparatus in order to prevent the occurrence of a hazardous explosive condition.